Method for quietly casting foamed metal

ABSTRACT

A novel vessel and an improved method of casting batch liquid materials which solidify on cooling or standing utilizing said vessel; the method is especially advantageous for casting foamed metals whereby a composition containing molten metal and a suitable foaming agent is prepared in one or more upright, openended vessels provided with suitable gaskets and seated against the bottom of a mold. When the composition is ready to be cast, the vessels are vertically separated from the mold bottom so that only the lower ends of the vessels contact the composition as it quietly flows into the mold.

United States Patent 91 Jarema et al.

[ 1 March 6, 1973 METHOD FOR QUIETLY CASTING FOAMED METAL [75] Inventors: Chester P. Jarema; Leonard M.

Niebylski, Birmingham, both of Mich.

[73] Assignee: Ethyl Corporation, New York, NY.

[22] Filed: Dec. 9, 1971 [21] Appl. No.: 206,309

Related US. Application Data [62] Division of Ser. No. 50,139, June 26, 1970, abandoned.

[52] US. Cl. ..164/79, 164/136, 264/54 [51] Int. Cl. ..B22d 27/20, B22d 37/00 [58] Field of Search .....l64/55, 79, 133, 136; 264/54 [56] References Cited UNITED STATES PATENTS 4/1961 Willemsenm, ..25/120 FOREIGN PATENTS OR APPLICATIONS OTHER PUBLICATIONS Transactions of American Foundrymans Society, Vol. 69, pp. 65-79 (1961).

Primary Examiner-Robert D. Baldwin Attorney-Donald L. Johnson et a1.

[57] ABSTRACT A novel vessel and an improved method of casting I batch liquid materials which solidify on cooling or standing utilizing said vessel; the method is especially advantageous for casting foamed metals whereby a composition containing molten metal and a suitable foaming agent is prepared in one or more upright, open-ended vessels provided with suitable gaskets and seated against the bottom of a mold. When the composition is ready to be cast, the vessels are vertically separated from the mold bottom so that only the lower ends of the vessels contact the composition as it quietly flows into the mold.

9 Claims, 8 Drawing Figures PAH'lNHU -AR 613 SHEET 10F 2 .l 2 3 ///A A ////////////////Efl//////Z//////// w \\\\\\\\\\\M A FIGURE 2 FIGURE 1 FIGURE 3 FIGURE 4 INVENTOR.

I CHESTER P. JAREMA LEONARD M.NIEBYLSK| PATENTED 61973 SHEET 2 OF 2 Al B Q 8' FIGURE 5 FIGURE 5A El -5E lo' B-B l I' l E It? Al FIGURE 58 FIGURE 6 INVENTOR.

CHESTER P. JAREMA LEONARD M NIEBYLSKI CROSS REFERENCE TO RELATED APPLICATION This application is a Division of copending application Ser. No. 50,139, filed June 26, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention is directed to an improved method of batch casting liquid materials especially foamed metals, utilizing a novel vessel.

Casting, that is, transferring a liquid material to a mold where it will subsequently solidify is ordinarily accomplished by pouring the liquid material out of the vessel containing the liquid material directly into a mold. Simple examples are pouring a gelatin dessert into a mold, pouring water into an icecube tray for freezing, and the like. Where transfer time is an important element in casting, e.g. polyurethane foams, liquid elastomers, liquid resins, e.g. epoxy resins and polyester resin, metal foams and the like, pouring the liquid material from itscontainer into a mold can create problems such as poor mold filling, undesirable air entrapment, loss of material due to set up in the container and the like. The problem with casting foamed metals, such as foamed aluminum, is particularly perplexing because of the relatively short time interval between adding a foaming agent to the molten metal and foam formation. One expedient which has been utilized successfully in overcoming some of the aforesaid problems is the use of a continuous method of preparing and casting the liquid material. This continuous preparing/casting system has been applied to foamed metal casting as illustrated in the following U. S. Pat. Nos.: 2,937,938, 2,974,034, 2,983,597, 3,005,700, and 3,214,265. However, this expedient is not applicable to batch operations.

It has been discovered that in batch operations, a very rapid transfer of castable liquid material from the holding and/or preparing container into the mold can be achieved by using-a novel vessel in which the mold bottom serves as the bottom of the mixing vessel. Thus, especially when transfer time is important for example, with foamed metals, the transfer of liquid to the mold can be directly and efficiently accomplished with essentially no time lag by simply separating the mixing vessel from the mold when the liquid material is ready to be cast. In this way, the liquid material quietly, smoothly and rapidly flows directly into the mold, avoiding problems associated with pouring.

SUMMARY OF THE INVENTION An improved vessel for casting and/or preparing casting liquid materials comprises (a) one or more main body elements open at opposite ends which provide cavity for holding said liquid, and (b) a bottom element which seals the lower aforementioned open end and is also the bottom of a mold into which the material is to be cast. A feature of the vessel is that the bottom element and main body elements are completely vertically separable.

An improved method of casting liquid materials especially foamed metals utilizes said vessel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a section view through a vessel of the present invention. The main body element 1 is shown fully seated against the bottom element 4.

FIG. 2 is a section through the vessel of FIG. 1. It shows the body element 1 separated from the bottom element 4 permitting the liquid material 2 to flow into the bottom element 4.

FIG. 3 is a section through a vessel of the present invention having two body elements, 1 and 1'.

FIG. 4 is a section through the vessel of the present invention. It illustrates a hemispherical body element la.

FIG. 5 is a side view section of a substantially hemispherical main body element having a lower opening lb of different shape.

FIG. 5A is a top view section of FIG. showing the shape of the lower opening lb.

FIG. 5B is a partial section top view of FIG. 5 section at 8-H and the bottom element 4. It shows the pattern of the liquid material 2 flowing out of the main body element 1 into the bottom element 4.

FIG. 6 is a partial section view of a vessel of the present invention. It includes an illustration of a sectioned heating element 7 which surrounds the main body element 1. A platform 5 driven by a piston 6 holds the bottom element 4 in a sealing position against the main body element 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of this invention is a novel vessel for casting and/or preparing a castable liquid material. The vessel comprises (1) at least one main body element open at opposite ends in which the liquid material to be cast is held and (2) a bottom element which seals the lower of said open ends. The bottom element is also the bottom of a mold into which the liquid material is to be cast. When the liquid material is ready to be cast, the bottom element and main body elements are vertically separated. The liquid material thus immediately and directly flows into the mold (which is the bottom element). As compared to any standard technique of casting which requires a pouring operation, the present method utilizing the novel vessel substantially reduces the time lag between ready to cast" and cast; and since there is not actual pouring from one container into another, splashing and problems caused thereby are also virtually eliminated.

The method of casting liquid materials utilizing the vessel of the present invention is also an embodiment of this invention.

Referring to the drawings, FIG. 1 illustrates in cross '5 at A-A',

section a vessel of the present invention. The main body element 1 is open at both ends. It provides a cavity in which the liquid material 2 to be cast is held. The lower end of the main body element 1 is provided with a suitable gasket 3 against which the bottom element 4 is seated, thus sealing the main body element 1 and holding the liquid material 2 therein. FIG. 2 shows the vessel of FIG. 1 shortly after the two elements 1 and 4 are separated and the liquid material 2 flows directly into the mold or bottom element 4. FIG. 3 illustrates a vessel in which two main body elements 1 and 1' are utilized. The number of main body elements may be varied as the particular total system requires. FIG. 4 illustrates a vessel of the present invention in which the main body element 1 is hemispherical in shape. FIG. 5 shows a hemispherical main body element 1a with a lower opening 1b of different shape than the main body element 1. FIG. 5A shows that said opening 1b is substantially rectangular. FIG. 5B shows a top view of FIG. 5 at section B-B' in which the bottom element 4 or mold has the same shape (rectangular) as the lower opening of main body element 1. The desirability of the main body element 1, or at least the lower opening of said body element, and the bottom element or mold having substantially the same shape improves the liquid flow pattern by making it better coincide with the mold shape. FIG. 6 shows an assembly which includes a heatis ordinarily liquid orcanbe liquified as for example byheating, the present method is of especial value when batch casting liquid materials in which time from ready to cast to cast is of importance. Our method is especially of value with batch casting a liquid material which subsequently foams in the mold, especially when the liquid material is molten metal. By batch casting is meant preparation of a certain volume of liquid material which is then used to fill a discrete mold or molds. This is in contrast to continuous casting where the liquid materials are being mixed and fed continuously either to a discrete mold or to a moving mold for example, a shaped conveyor belt.

The present vessel may be constructed of any materials which are suitable for handling the particular liquid material which is to be cast. In other words, if the liquid material were corrosive, then a material of construction which would not be attacked by the liquid material should be used; and if a considerable amount of heat is required to liquify and prepare the material (e.g. metal) for casting, the material of construction should be sufficiently heat resistant. Thus, the properties and characteristics of the liquid material to be cast will help determine the type of construction material required for the present vessel.

Although the bottom element may seat directly against the lower open end of the main body elements, a gasket is more conveniently provided at the lower end to facilitate sealing. This is illustrated in FIGS. 1-4 and 6. This gasket material should be a material against which will withstand the conditions which are required for casting and/or preparing liquid materials. The gasket should also'be compressible. Thus, for example, for casting high temperature molten metals such as aluminum or titanium, an asbestos gasket and the like is suitable; for casting low temperature liquids such as polyurethanes, a butylelastomer or ethylene/propylene/diene terpolymer gasket may be used.

The size and shape of the main body elements and bottom element or mold which comprises the present vessel can also be varied as required. Ordinarily, where the main body element of the present vessel is also utilized to prepare the liquid casting material and agitation and mixing of the ingredients is required, then main body element shape which would facilitate such mixing would best be used. With reqard to the volumes of the main body elements and the mold or bottom element of the present vessel, there is no fixed relationship although ordinarily the volume provided by the main body elements should be adequate to hold sufficient liquid material to fill the mold or bottom element to the desired level. The size of the lower open end of the main body elements should also be adequate to permit the flow of liquid material into the mold to be accomplished in the time required for the system.

Although the shape of the main body element and the bottom element or mold of the present vessel are not directly interrelated, it is preferred that at least the lower open end of the main body element and the mold or bottom element be of similar shape .(see FIG. 5B for example). By maintaining 'sucha shape relationship, the flow pattern of the liquid material during the casting step is such as to effect a more uniform flow of liquid from the main body element into the mold or bottom element. Thus, for example, if a square mold served as the bottom element of a vessel of the present invention and the material to be cast required maximum mixing and agitation then a hemispherical main body element having a square opening at its lower end (see FIG. 5A for example) would provide a most efficient flow pattern for casting the liquid material. If desired of course, the shape of the entire body element may be uniform with said open end. It is also contemplated that the opening at the lower end of any shaped main body element could be changed to fit the shape of any mold by the use of a detachable lower end opening (see FIGS. 5 and 5B for example).

As disclosed above, the method of the present invention is especially applicable to casting foamed metals. Metals include substantially pure metals as well as alloys. Examples of useful metals are zinc, titanium, iron, lead, copper, tin, silver, platinum, their alloys and the like. A preferred foam metal for casting is foamed aluminum. By aluminum is meant substantially pure aluminum as well as aluminum alloys containing /o or more and preferably /o or more aluminum. The following aluminum alloys are examples of useful alloys for preparing such foam:

Alcoa alloy 7075 (1.6/o Cu, 2.5/o Mg, 0.3/o Cr, 5.6/o Zn, remainder Al) 2024 (4.5/o Cu, 0.6/o Mn, 1.5/o Mg, remainder 5086 (0.45/o Mn, 4.0/o Mg, 0.1/o Cr, remainder 6063 (0.4/o Si, 0.7/o Mg, remainder Al) Almag 35 (68/o Mg in A1) 1000 series Al (99.6/o minimum A1) 2011 (5.5/o Cu, 0. 5/o Pb, 0.5/o Bi (remainder A1) 2218 (4.0/o Cu, l.5/o Mg, 2/o Ni, remainder Al) 3005 (l.2/o Mg, 0.4/o Mg, remainder A1) 4042 (12.2/o Si, 0.9/o Cu, l.l/o Mg, 0.9/o Ni,

remainder Al) Alcoa alloy 4043 (5/o Si, /o Al) 8280 l .5/o Si, l.0/o Cu, 0.5/o Ni, remainder Al) Magnalium 70lo Al, 30/o Mg In general, preparation of foamed metals involve blowing the molten metal with a suitable gas generating (cellulating or foaming) agent such as magnesium hydride, titanium hydride, zirconium hydride and the like. Air properly entrained in a molten metal may also be used in preparing metal foam. Where a blowing agent such as a metal hydride, preferably zirconium hydride, is used, a viscosity controlling additive may be added to the molten metal during the preparation of the foam to help control the foam density and pore uniformity. The viscosity controlling agent is generally added before the foaming agent (or air) is introduced into the molten metal. Representative examples of foam compositions and methods of preparing the molten mixtures are found in the patents cited above.

To illustrate the advantages of the present vessel and method in casting foamed aluminum, a batch of molten aluminum alloy containing zirconium hydride blowing agent and CO as a viscosity control additive was prepared in a heated mix pot with adequate agitation. The mix pot was provided with a bottom which could be opened to permit the molten aluminum mixture to pour into a mold placed beneath the pot. When the molten aluminum mixture was ready for casting the bottom of the pot was opened, and the molten aluminum mixture poured into a mold held beneath the mix pot. The cast aluminum mixture in the mold was then cooled externally by means of air blowers. The resultant molded aluminum foam was examined and found to have imperfections caused by splashing and splattering in the center of the mold where the molten metal poured from the mixing pot. This splashing and splattering also caused envelopment of air which resulted in further defects in the foam.

Substantially the same composition of molten aluminum alloy containing zirconium hydride and CO was then prepared in a vessel of the present invention. The mixture was prepared in substantially the same way using the same agitation system and mixing cycle. The foam was then cast into a mold, as per the present method, by lowering the mold (or bottom element) from the main body element until all the molten aluminum mixture had flowed into the mold. Transfer of the molten metal from the main body element was quiet, rapid and essentially complete (compared to the mixed pot method) before the foaming occurred. Thus, the foam was generated in the mold and substantially filled the mold. The cast aluminum foam was then cooled by means of air blowers. Examination of the cast aluminum foam showed it to be substantially free from any of the splashing and splattering defects and consequent air envelopment defects using the aforesaid mixing pot. Furthermore, the foam prepared using the present method was more uniform throughout than the foam produced using the aforesaid mixing pot method.

It is readily apparent then that the present vessel and method of casting liquids and especially molten metals and foams such as aluminum foams, provides a means for substantially improving batch casting in liquids. In addition to the readily evident substantial improvement in quality of the final cast product, the present vessel and method offer the following additional advantages compared with conventional mix pot/pour systems:

1. The system is simple in operation.

2. The vessel has no moving parts and consequently dimensional tolerances are not critical, 3. Transfer of liquid material from main body element to bottom element or mold is rapid, direct and quiet flow" is insured.

4. Loss of casting liquid caused by residual liquid being retained in the main body cavity after casting is substantially reduced; and in the case of foamed metals such as aluminum, this also effects more accurate control of the foam density.

The present invention has been disclosed above. It encompasses two embodiments: (l) a novel vessel, and (2) a method for casting liquid materials especially foam metals, utilizing said novel vessel.

Claims to the invention follow.

We claim:

1. An improved method for casting foamed metal which comprises A. preparing a composition containing molten metal and a suitable foaming agent, in a vessel which comprises 1. one or more upright main body elements which a. define cavity for holding said composition,

and b. are each open at opposite upper and lower ends, and 2. a bottom element (a) which is seated against and closes the lower open ends of said main body elements, said lower open ends being provided with suitable gasket against which said bottom element is seated, and (b) which is also the bottom of a mold into which said composition is to be cast, said main body elements and said bottom element being completely vertically separable, and

B. vertically separating said bottom element and said main body elements when said composition is ready to be cast, so that only the lower ends of said main body elements contact said composition as it flows into said bottom element,

whereby said composition flows directly, substantially completely and quietly into said mold.

2. The method of claim 1 wherein said vessel has one main body element.

3. The method of claim 1 wherein said separation is effected by lowering said bottom element from said main body elements.

4. The method of claim 2 wherein said separation is effected by lowering said body element from said main body elements.

5. The method of claim 1 wherein said separation is effected by raising said main body element from said bottom elements.

6. The method of claim 1 wherein said separation is effected by simultaneous movement of said main body elements and said bottom element in substantially opposite directions.

7. The method of claim 1 wherein said molten metal is at least /o aluminum.

8. The method of claim 7 wherein said foaming agent is selected from titanium hydride and zirconium hydride.

9. The method of claim 7 wherein said foaming agent is zirconium hydride.

* III 

1. one or more upright main body elements which a. define cavity for holding said composition, and b. are each open at opposite upper and lower ends, and
 1. An improved method for casting foamed metal which comprises A. preparing a composition containing molten metal and a suitable foaming agent, in a vessel which comprises
 2. a bottom element (a) which is seated against and closes the lower open ends of said main body elements, said lower open ends being provided with suitable gasket against which said bottom element is seated, and (b) which is also the bottom of a mold into which said composition is to be cast, said main body elements and said bottom element being completely vertically separable, and B. vertically separating said bottom element and said main body elements when said composition is ready to be cast, so that only the lower ends of said main body elements contact said composition as it flows into said bottom element, whereby said composition flows directly, substantially completely and quietly into said mold.
 2. The method of claim 1 wherein said vessel has one main body element.
 3. The method of claim 1 wherein said separation is effected by lowering said bottom element from said main body elements.
 4. The method of claim 2 wherein said separation is effected by lowering said body element from said main body elements.
 5. The method of claim 1 wherein said separation is effected by raising said main body element from said bottom elements.
 6. The method of claim 1 wherein said separation is effected by simultaneous movement of said main body elements and said bottom element in substantially opposite directions.
 7. The method of claim 1 wherein said molten metal is at least 80*/o aluminum.
 8. The method of claim 7 wherein said foaming agent is selected from titanium hydride and zirconium hydride. 